US cable-and-content behemoth Comcast issued a brazen challenge to News Corp. mogul Rupert Murdoch by offering a 22 billion pound ($31 billion) cash bid to buy Sky, challenging Murdoch's Twenty-First Century Fox - which is trying to buy the 61% of the company that it doesn't already own - and Walt Disney, which recently purchased nearly all of the entertainment assets once owned by the Murdoch-controlled 21st Century Fox.

Comcast's bid comes out to GBP12.5 per share in cash for the UK broadcaster, a 16% premium to the GBP10.75 per share that Fox recently offered for the 61% of the company it doesn't already own.

Sky shares soared nearly 20% on the news.

As Reuters points out, Sky services 23 million homes across Europe and is known for its technological innovation. Murdoch has been trying to gain 100% control of the company but has been stymied by British regulators, who have raised concerns about his stewardship stemming from the News of the World phone-hacking scandal and his already vast influence over UK media. Murdoch already owns several of the UK's most widely circulated print publications, as well as his 39% stake in Sky, According to Reuters.

The UK competition regulator has said the bid raises media plurality concerns because taking full control of Sky News would give Murdoch’s family too much control over UK news media. The family trust controls Fox and News Corp, the publisher of the Sun and the Times.

The Guardian reported that Comcast is also exploring a bid for 21st Century Fox's entertainment assets, which include Sky and the 20th Century Fox film studio. Such a bid could potentially disrupt the $66 billion deal that Fox struck with Disney to purchase the entertainment assets.

Sky has 1,300 employees in the UK working in broadcasting and film and TV production, including the firm behind Downton Abbey. Comcast promised that Sky’s headquarters would remain at Osterley in southwest London. In what appears to be a Murdoch snub, the company in its press release noted that it likely wouldn't have any trouble securing the regulatory approvals.

"Comcast intends to use Sky as a platform for growth in Europe. We already have a strong presence in London through our NBC Universal international operations, and we intend to maintain Sky’s UK headquarters," said the Comcast chairman and chief executive, Brian Roberts.

"Adding Sky to the Comcast family of businesses will increase our international revenues from 9% to 25% of company revenues. We would like to own the whole of Sky and we will be looking to acquire over 50% of the Sky shares. We are confident that we will be able to receive the necessary regulatory approvals."

Dissatisfied with the Murdoch bid, Sky investors have already been calling for an increase of 10% to 25%, up to £13.40 a share Following Sky’s £3.57 billion deal to secure the lion’s share of the Premier League broadcasting rights at a 14% discount earlier this month.

Analysts have already chimed in this morning, saying they don't expect Comcast's bid to be the last offer for Sky. Hedge fund manager Crispin Odey said the Murdochs will be furious about the bid, saying they will regard this as "tanks on their lawn."

Mirabaud’s Neil Campling says investors can expect a counter-bid as Fox likely won't walk away from Sky given how advanced the regulatory clearance process is. Campling added that this bid "marks a floor, not the end to this particular saga." Sky would be a good strategic fit for Comcast because it would allow it to diversify away from the US. While Disney would clearly benefit from owning Sky's European assets, it might conclude that it already has enough to do in the US.

An analyst at Jeffries said a counter "well above 12.5 pounds now becomes very likely."

Now we wait for Fox and Disney to comment on the bid and the inevitable counteroffer.

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In a Reuters Breakingviews post published only moments ago, columnist Liam Proud pointed out that Comcast boss Brian Roberts could be driving a wedge between Disney and Fox because it creates a serious dilemma for Murdoch: enter a bidding war for Sky, or re-think his deal to sell Fox’s entertainment assets to Disney.

Comcast’s offer will go ahead if just over 50 percent of Sky shareholders accept it. That means Murdoch’s 39 percent stake will not be enough to block the deal.